Thyroid and Antithyroid agents

Question 1

What does the hypothalamus release to stimulate the thyroid? what does it act on?

Answer 1

thyrotropin releasing hormone

Pituitary

Question 2

What does the pituitary release to stimulate the thyroid?

Answer 2

thyroid stimulating hormone

Question 3

Does T3 and T4 stimulate the hypothalamus and pituitary?

Answer 3

No negative inhibition

Question 4

What are the 3 main actions of thyroid hormones?

Answer 4

1. increase basal metabolic rate
2. increase heart rate and cardiac output
3. stimulate protein synthesis

[also stim carb metabolism and lipolysis, REDUCE insulin sensitivity]

Question 5

What carries thyroxine and triodothyronine in the blood?

Answer 5

thyroxine binding globulin

Question 6

What inhibits the release of T3 and T4?

Answer 6

iodide

Question 7

Does MMI effect peripheral conversion of T4 to T3?

Answer 7

No, just PTU although they both do the oxidation , iodination and coupling inhibition

Question 8

In Grave’s disease, are the hypothalamus and the pituitary hyperactive?

Answer 8

NO! they are actually inhibited by negative feedback of T3 and T4. low TSH

Question 9

What is the target for treatment in hyperthyroidism?

Answer 9

decrease synthesis and or release of thyroid hormones

Question 10

How do we administer PTU or MMI? onset of action?

Answer 10

1. Orally

2. slow (weeks) takes time to deplete thyroid hormone stores

Question 11

T-F–PTU works faster than MMI, but is less potent and has a longer duration of action?

Answer 11

False- shorter duration

Question 12

T-F–preganant women with hyperthyroidism should be treated with MMI in the 1st trimester? What about when nursing?

Answer 12

False…PTU

Both can be used when nursing

Question 13

T-F-PTU and MMI starts with low doses and gradually progresses? how long is treatment?

Answer 13

False-opposite is true

Treatments are long- 12-18 months

Question 14

What is incidence of relapse from PTU and MMI treatment?

Answer 14

50%

Question 15

What is time course of action for iodide treatment

Answer 15

fast but the effect is transient–rarely used as a sole therapy

Question 16

When should we never use 3-121 generic iodion?

Answer 16

pregnant women or nursing mothers

Question 17

After thyroidectomy, what is required in 80-90% of cases?

Answer 17

replacement therapy to treat resulting hypothyroidism

Question 18

Why are beta-adrenergic antagonists used in hyperthyroidism?

Answer 18

used to alleviate symptoms associated with increased CV activity

Question 19

What sky rockets in primary hypothyroidism, (HASHIMOTOs disease)?

Answer 19

1. thyrotropin releasing hormone TRH

2. Thyroid stimulating hormone TSH

Question 20

What lacks in secondary hypothyroidism? Tertiary hypothyroidism?

Answer 20

1. TSH

2. TRH

Question 21

what does perchlorate cause as a side effect? iodine deficiency?

Answer 21

hypothyroidism for both

Question 22

In hypothyroidism do we see hyperthermia or hypothermia?

Answer 22

hypothermia

along with drowsiness, sluggishness, mental/growth retardation

Question 23

What is severe hypothyroidism also known as?

Answer 23

myxedema

Question 24

What is the extreme expression of severe long lasting hypothyroidism? how do we treat?

Answer 24

myxedema coma- treated with IV T3 in addition to emergency procedures

Question 25

Do synthetic analogs of T3 and or T4 that act as agonists of the thyroid hormone receptor exist?

Answer 25

not yet available

Question 26

How long is treatment of hypothyroidism?

Answer 26

life long

Question 27

How much more hormone do children require than adults in treatment of hypothyroidism?

Answer 27

10x more /kg

Question 28

Is T3 or T4 more potent? longer half life? higher oral absorption? more expensive?

Answer 28

T3
T4
T3
T3

Question 29

Who should we be careful in treating with thyroid hormones T3 and T4?

Answer 29

1 patients with cardiac disease

2. pregnant women (they require 30-50% more hormone